Matting is used in computer graphics and computer vision for a variety of purposes, including special effects in television shows and movies. Matting involves separating background and foreground regions in an image (e.g., a still image or a video image). Typically, this process is based on a model of an image I as a mixture of a foreground F and a background B in accordance with the following equation:I(x)=α(x)F(x)+(1−α(x))B(x)  (1)where x is a pixel location and αε[0, 1] is an alpha mask that quantifies the mixture. Matting involves solving for F, B, and α based on I. A common method of extracting alpha mattes from a video involves placing the foreground objects in front of uniformly colored background screens, e.g., blue or green backgrounds. Among the problems with such an approach are the constraints that the foreground object should not include any of the background colors and care should be taken to avoid adding a colorcast of the background onto the foreground.
What are needed are improved systems and methods of generating an alpha matte that does not involve the use of colored backgrounds.